1. Field of the Invention
The present invention relates to an endoscope for use in medical and other procedures. More particularly, the present invention provides an improved means of transmitting light from an ocular end to an objective end of the scope in order to illuminate the area under observation. The present invention also provides an improved light and image transmitting lens portion which can be a disposable item.
2. Description of Prior Art
Endoscopes are widely used today to assist in a variety of medical and other procedures. With the growing importance of the practice of minimally invasive surgery, the need for high quality and low cost endoscopes has grown substantially.
A typical endoscope is generally divided into three main sections: an objective section; a relay section; and an ocular section. The objective section is that portion of the endoscope that is inserted into the body. The relay section transmits the image from the objective section to the ocular section. The ocular section magnifies the image for viewing by an operator.
Basically, two types of endoscopes are employed for surgical medical procedures--flexible endoscopes and rigid endoscopes. The flexible endoscope uses an optical fiber bundle to relay the image from the objective section to the ocular section. The endoscope is flexible because of the ability of the fiber bundle to bend while still transmitting an image.
The rigid endoscope uses lenses instead of fibers to transmit the image. The main advantage of using lenses to relay the image is that lenses provide better resolution and brightness, the brightness being determined by the optical invariant of the relay section. Thus, rigid endoscopes are preferred for many medical procedures where image quality is crucial.
The use of radial gradient-index rod lenses, usually referred to as "GRIN" lenses, in endoscopes is well known. These lenses are commercially available from the Nippon Sheet Glass Co., Ltd. and its U.S. affiliate, NSG America, and are sold under the trademark SELFOC.RTM..
Endoscope designs can be quite complex in order to view and transmit the proper images from inside the body to the operator, as well as to attempt to compensate for chromatic aberrations and distortions. In addition to the lens components, a typical endoscope also uses a fiber bundle to transmit light from the ocular section to the area under observation. The fiber bundle is generally circular and surrounds the lenses interior to the endoscope's outer casing.
The use of fiber bundles for illumination in endoscopes suffers from a number of drawbacks. First, fiber bundles can be quite difficult to manufacture and add substantial cost to the overall endoscope. Second, fiber bundles transmit light to the end of the endoscope in the same circular configuration as it is put in, making for poor illumination of the image plane. Another major drawback with this form of endoscope is its inability to withstand the rigors of sterilization.
The use of an endoscope as a medical instrument requires sterilization between operations. Typically, hospitals employ the high temperature and pressure of an autoclave to sterilize medical instrumentation. Unfortunately, due to its size, the interior of the endoscope experiences very high temperatures during sterilization which can cause separation of the adhesive in the fiber optic bundle. Additionally, the cement holding connecting adjacent lenses can be compromised, allowing moisture to invade the lens and create fogging. Thus, although existing endoscopes function quite well, none is capable of repeatedly withstanding the demands of the sterilization process.
Accordingly, it is a primary object of the present invention to provide an endoscope with an improved ability to provide even illumination of an area under observation.
A further object of the present invention is to provide an endoscope that does not require the use of expensive and fragile fiber optic bundles to transmit light to the area under observation.
Yet another object of the present invention is to provide an endoscope that is relatively simple and inexpensive to manufacture.
An additional object of the present invention is to produce a reliable endoscope that may be manufactured so inexpensively that it is readily disposable.
These and other objects and advantages of the present invention will become apparent from consideration of the following description and drawings.